This invention relates to assays for analytes in a liquid sample such as a body fluid. More particularly, the invention relates to a method and apparatus for the detection of a ligand in a body fluid such as urine or blood.
Many types of ligand-receptor assays have been used to detect the presence of various substances in body fluids. These assays usually involve antigen antibody reactions or synthetic conjugates and are visualized by radioactive, enzymatic, fluorescent, or visually observable carbon or metal sol tags. In these assays, there is a receptor, e.g., an antibody, which is specific for the selected analyte and a means for detecting the presence, and often the amount, of the ligand-receptor reaction product.
The assays must be highly sensitive because of the often small concentration of the analyte of interest in the test fluid. False positives can also be troublesome, particularly when there are interfering substances in the body fluid that are able to produce a positive test result in the absence of analyte.
It is an object of this invention to provide a rapid, sensitive method for detecting analytes in body fluids. Another object is to provide an assay that has high sensitivity and fewer false positives than conventional assays.